Having read the various trains of thought and pondered for a while; several fundamental questions come to mind:
1) How is mana generated? A mixed approach of crystals nodes, the SOV channeler (at some base level) buildings or population (but not both) and augmented by relics and or spell effects seems to me a managable approach allowing for small high magic nations and large geographic empires to both be viable options though actuall game play may turn out to favor one option over the other.
2) Once mana is aquired is it in several pots or one large pot? I strongly opt for the single well of mana option, that elemental crystals are a component (perhaps not the only one...) of spells particularly large spells is also good.
3) Should there be a limit to the size of the mana pool? No, capping it would disadvantage several styles of play.
4) How is the mana used? This is the real core of much of the discusion. I have several uses but lets begin with spells.
I propose the following basic effects based spells broken into two broad catagories non-combat and combat:
Global: Said spell impacts the entire world in some way altering an aspect of game mechanics (but not by much); such a spell would have a permanent effect (that perhaps could be countered or further augmented by another SOV?). High initial casting cost and may or may not have a maintenance drain.
Nation: Said spell impacts your nation or some aspect of your nation only or another nation or some aspect of another nation only (this should be obvious and a hostile act!); such a spell should have a high initial cost and a maintenance cost (that would be a steady drain on your mana pool).
Local: Said spell impacts a particluar area (like a city, or an army) or an enemy city or army and have a mixed bag of high to medium casting cost, some spells will have a mana maintenance cost as well.
Specific individual or unit: Could be benificial or detrimental to the unit, some of this type will be combat (tactical) spells, some will be non-combat, some will be both. The mana cost will be effects (balanced) based and some may have a maintenance drain.
Tactical spells: This would include a lot of small and large AoE, and single target spells that heroes, summoned creatures, or the SOV caster could unleash.
5) Will there be limits on how the SOV can unleash mana? Yes. I propose the following limits. The SOV (when his avatar is not actually in the tactical combat) is limited to X mana per engagement. The X can be adjusted through experience and/or research, there may be additional limits imposed during balancing feedback. 5B) The heroes (unique persons in service to the SOV) should have some ability to tap the SOV's mana pool to cast additional spells. A heroes abilty to do so is based on experience, magic items created by the SOV for that purpose, and augmentation spells.
6) Will it matter if the SOV is holed up in a community (tower?) or going Gandalf? Yes, the SOV should research faster in a settlement and there may be structures (library/museum) that can augment that research, doing so however deprives you of a VERY powerful tactical unit.
7) Aside from spell casting what else is mana used for? Mana should have several uses, the first and most obvious is casting spells and maintaining spells already cast. The second is magic item creation. The third is modifying research time. Let me explain. A spells research time should be based on the power of the spell as determined by its duration, AoE, and what it does and is largely determined by its casting cost. Once considered this will determine the base time to research. Mana (from the pool) can be expended to reduce the time to research which will enable a spell to be available sooner.
8) Are spells available in serial fashion or in parallel? I prefer parrallel, the SOV can expend mana to influence when a desired spell is available. The SOV should be able to research/study/decipher a number of spells at once the draw back is this will adjust the time to aquire by that percentage. So if it would have taken 6 turns to aquire the tactical spell lightning bolt (assuming the final build is still turn based on the global scale) it will take 12 turns if a second spell is being researched as well. Mana can be expended to reduce the research time of either or both spells.
9) Should there be precurser spells? Yes, while not a spell tech tree per se, some spell knowledge should build on others. For example: the tactical spell lightning bolt could be a precurser to the non-tactical spell lightning bolt that targets a city or an army. The difference is the scale. That said, such precurser spells or even a string of related precurser spells should be used where they make sense and sparingly. I for one would rather not research a spell I don't intend to use just because it is a precurser to one I want badly.
10) Are spells instantanious or near instantanious? Yes and no. Some spells should be cast very quickly, esp tactical combat spells, that said even some tactical spells should have a non-instantious casting time. This assumes tactical combat is not turn based. The big spells (perhaps called ritual spells mentioned in numerous earlier threads) would take time and preparation to cast and would effectively trap the SOV to some local while the spell is being cast. Of course if the SOV has a hero who has aquired the abilty to tap enough mana to cast (some) ritual spells then that hero could do so as a proxy to the SOV, freeing the SOV to do other things.
11) What happens if the SOV avatar dies? Game over!!!!! Now there could be precase spells that could revive a weakened version of the SOV.......
12) Using the above guidelines there is immense potential to populate the world with spells, I even envision a spell generator where by the player punches in a desired outcome with a set of variables (within limits) and the game engine produces a custom spell with appropriate research time. The player could choose the spell animation as one of the variables. The game designers could of course not opt for this tool in game (cough modders), but I imagine most spells (from the designer point of view) to be little more than a spread sheet of stats linked to an or a series of animation sequences.
Darvroth